High frequency oscillation generator



Dec. 30, 1-941. E. HEINECKE i 2,267,914

HIGH FREQUENCY OSGILLATION GENERATO Filed June 23, 1959 Patented Dec.30, 1941 UNITED STATES orricc HIGH FREQUENCY OSCILLATION GENERATGRApplication June 23, 1939, Serial No. 280,696 In Germany July 1, 1938 l1 Claim.

This invention relates to high frequency circuits, and more particularlyto new and useful improvements in circuit arrangements for ultra highfrequency oscillators and consists in certain features of novelty whichwill be fully understood from the following description and be pointedout in the appended claim, reference being made to the accompanyingdrawing, in which Fig. l shows a circuit arrangement of conventional artexplanatory of my invention, while the Figs. 2 and 3 diagrammaticallyshow two different embodiments according to my invention,

It is frequently desirable in oscillation generating systems having avoltage divider connected in the output circuit of an electron dischargedevice to secure constant phase relations and a constant voltage ratioof Ul/U2=-K across this output circuit, for the purpose ofneutralization, for example. A Voltage divider of conventional type asschematically shown in Fig. 1 consists of two condensers Cl and C2 andan adjustable tuning variometer L which together constitute a fourpolehaving a series branch, i. e. the variometer coil L of indefinite spacecapacitance, and two cross branches such as condensers interconnectedbetween the input and the output terminals, respectively. Assuming thatthe space capacitance CR of the series branch with respect to the crossbranches CI and C2 is neglectable, approximately the desired voltageratio of would be obtained which is constant and cophasal. This desiredvoltage ratio, however, cannot be maintained in high frequency operationbecause of the fact that the space capacitance CR assumes a value whichis in the order of that of the cross branch condensers CI and C2 so thatthe effect thereof alters the conditions of the circuit arrangement fromwhich follows that not only the absolute magnitude of the voltage ratiobut also the phase conditions are considerably changed.

It is the object of my invention to overcome the last mentioneddisadvantage and to provide means which allow the desired voltage ratioto be maintained constant also at high and ultra high frequencyoperation.

According to the main feature of this invention, the space capacitanceeffect of a series branch connected in the output circuit of an ultrahigh frequency generator is nullied by the provision of shielding meanssurrounding this branch, and by electrically connecting the shieldjoinedto the series branch. Such electric connection must be possiblynon-inductive. The capacity to ground of the shielding means, preferablyof tubular shape, is thus effective as a shunt capacity with respect tothe cross branch, or in other words, acts in parallel with a condenserof the voltage divider, in which case either of the cross branchcapacities must be correspondingly decreased. It is thus possible bymeans ofrsuch shielding and its electric connection to one end of theseries branch to convert the fourpole, as formed by the series branch inconjunction with its space capacitance and as such undesirable in utlrahigh frequency operation, into a desired circuit arrangement in whichthe capacity acts as a lumped capacity at the end of the series branchor coil.

The Fig. 2 shows one embodiment according to this invention. A voltagedivider constituted by the two capacities CI and C2 is connected acrossthe output circuit of an electron tube R. Reference letter L denotes atuning coil, the distribn uted space capacity of which is renderedinefing means to a point at which a cross branch is 55 fective for thedesired phase relation by means of a shielding cylinder Z since thismember is electrically connected with one end of the coil L, whilst itscapacity CZ to ground is shunted across the capacity C2. It is obviousthat the same result will be obtained if the cylinder Z would beelectrically connected in parallel with the capacity CI instead of thecapacity C2.

A further embodiment of my invention is shown in Fig. 3, in which theshielding cylinder Z is subdivided into two halves, the ends of whichbeing connected to the junction points of the coil and the capacities CIand C2, respectively. Also in this case the Voltage ratio U1/U2=-K maybe maintained even at ultra short wave operation by adjusting thecapacities CI and C2 of the voltage divider so as to correspond to theshunt capacity CZ.

What is claimed is:

A fourpole network comprising a series branch and a plurality of crossbranches, shielding means consisting of two halves, each halfsurrounding a portion of said series branch, one-half being electricallyconnected to the junction point between said series branch and one ofsaid cross branches and the other half being electrically ,connected tothe junction point between said series branch and another of said crossbranches to constitute leakage paths directly shunted across said crossbranches.

ERICH HEINECKE.

